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Date: Mon, 28 May 2018 14:07:53 +0300
From: Dan Carpenter <dan.carpenter@oracle.com>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
        linux-media@vger.kernel.org,
        Kieran Bingham <kieran.bingham@ideasonboard.com>
Subject: Re: [GIT PULL FOR v4.18] R-Car VSP1 TLB optimisation
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On Mon, May 28, 2018 at 01:54:18PM +0300, Laurent Pinchart wrote:
> Hi Dan,
> 
> Thank you for your quick reply.
> 
> On Monday, 28 May 2018 13:20:49 EEST Dan Carpenter wrote:
> > On Mon, May 28, 2018 at 11:28:41AM +0300, Laurent Pinchart wrote:
> > > and I still get the same warning. I had to write the following (which is
> > > obviously not correct) to silence the warning.
> > > 
> > >         if (pipe->num_inputs > 2)
> > >                 brx = &vsp1->bru->entity;
> > >         else if (pipe->brx)
> > >                 brx = pipe->brx;
> > >         else if (!vsp1->bru->entity.pipe)
> > >                 brx = &vsp1->bru->entity;
> > >         else {
> > >                 (void)vsp1->brs->entity;
> > >                 brx = &vsp1->brs->entity;
> > >         }
> > > 
> > > Both the (void)vsp1->brs->entity and the removal of the !drm_pipe->
> > > force_brx_release were needed, any of those on its own didn't fix the
> > > problem.
> > 
> > The problem in this case is the first "brx = &vsp1->bru->entity;".
> > Smatch assumes &vsp1->bru->entity can be == to pipe->brx and NULL.
> 
> Why does smatch assume that &vsp1->bru->entity can be NULL, when the previous 
> line dereferences vsp1->bru ?

I'm talking about when pipe->num_inputs > 2.  For the second
"brx = &vsp1->bru->entity;" assignment, then Smatch parses it correctly
as you say.

regards,
dan carpenter